1. Field of the Invention
This invention relates to special holographic images that are formed so as to provide security when viewed under special conditions and more specifically to a process for making multiple transference of these images on to paper.
2. Description of the Prior Art
Holographically enhanced materials are well known in the prior art and they have been fully described in my previously filed and issued patents described above. These materials include a number that have been used to enhance products with which they are associated such as wrapping papers, papers, cardboard boxes and the like. Also, holographically enhanced images can be used on credit cards and the like in order to provide security since the image is difficult to reproduce. Preparation of the holographic image is a well-known process but has not been widely used until the discovery of my unique processes for multiple transference of a metallized image onto alternative supports. A special novel support is a paper support, which heretofore could not be enhanced with a holographic image, because the support was too fragile. This element and process is well described in the aforementioned related patents above. The preparation of holographic materials is also described fully, among other references, in the Holography Handbook, Unterseher et al., 2nd Edition (1996), Ross Books, Berkeley, Calif.
Typical security holographic materials are exemplified in U.S. Pat. No. 3,894,756. Here a coded hologram is placed within an element such as a security ID card, for example. In order to unscramble the coded hologram a complicated beam-unscrambling device must be employed. When the beam is shown on to the coded hologram the image is formed and can be viewed. Another security system is described in U.S. Pat. No. 4,140,373. In this reference overlapping holograms are applied to the desired layer, one of said overlapping hologram being visible only by coherent light (e.g. laser light). When this coherent light is applied, the so-called invisible hologram can be seen. U.S. Pat. No. 4,400,616 describes yet another security system in which an identification card can be made, for example, by laminating one or more planar transparent wave-guide holograms to a support. By placing a grating over the resulting product, said grating being receptive to a particular wavelength, the desired image can be illuminated. Another reference, which describes a system and method for identifying a coded hologram, is U.S. Pat. No. 5,825,475. In this particular invention, a hologram is recorded on a substrate using a particular wavelength of light. By illuminating the hologram with that particular wavelength of light, the image can be viewed.
As can be seen from perusing these many prior art references, the making, manufacturing and selling of products that contain so-called hidden holograms is a complicated process involving a large number of steps and complicated equipment and viewing apparatus. Each element must be manufactured separately and thus it is a costly process.
Recently a newer and improved system for manufacturing the so-called hidden holograms has been found. In this system, a photosensitive resist layer is used. Part of the photosensitive layer is masked and a first hologram (white lightxe2x80x94non-coherentxe2x80x94viewable) imaged on the un-masked area. The mask is then removed and another hologram (laser lightxe2x80x94coherentxe2x80x94viewable) imaged on the unexposed area. Since there are now two holograms applied to this layer, one cannot be viewed directly by standard illumination methods and must be illuminated by reflecting coherent light (e.g. a laser) at a 90xc2x0 angle on to a viewing surface (e.g. a white reflective surface such as white paper, for example). Although this unique and useful system can produce security-type hidden holograms there are no methods for commercialization of the process so that it can be used extensively throughout the commercial industry.
There is a pressing need to make, manufacture and sell materials, which contain hidden holograms in order to prevent fraud. For example, counterfeit elements such as tobacco and other products are currently being sold throughout the world costing manufacturers and distributors considerable losses. If there were a simple and easy method for imparting a hidden hologram within the paper products used to contain and wrap these products, among many others, it would be a simple matter to trace down the counterfeiters. Thus, it is an object of this invention to impart hidden holograms in a cost-effective manner repetitively on to wrapping papers.
These and yet other objects are achieved in a holographic element comprising a paper support having two flat surfaces, one of said surfaces having in order:
a. an adhesive layer, and;
b. a metallized holographic image,
wherein said metallized holographic image comprises at least two holograms therein, one of said holograms being visible only by non-coherent light and the other of said holograms being visible only by coherent light, and wherein a plurality of holographic images are formed on a photosensitive element on a polymeric support by at least two imaging steps and wherein said holographic images are then metallized and overcoated with an adhesive later, and whereby said metallized holographic image is subsequently transferred to said paper support from said polymeric support by laminating the adhesive layer coated over said metallized holographic image to said paper support at a temperature between 0xc2x0 C. and 150xc2x0 C. and a pressure greater than 1 pound per square inch and subsequently delaminating said polymeric support from said paper support substantially transferring all of the metallized portion of the holographic image to said paper support and leaving the holographic image on the polymeric support suitable for reuse.
In the process of this invention, a photosensitive polymeric support is prepared and at least two holographic images are placed thereon. The first holographic image is placed on the photosensitive polymeric support in a conventional manner, after masking over a portion of the photosensitive layer contained thereon. After removal of the photomask, a second holographic image is imparted in the unexposed areas of the photosensitive layer. Both holographic images are then metallized and subsequently transferred to a paper support, the holographic image having first been over-coated with an adhesive layer. Specific temperatures and pressures are required to transfer only the metallized portions of the holographic images, leaving the holographic images remaining on the polymeric support, after delamination. The holographic images may then be remetallized for reuse.